Ballistic vests have saved the lives of many law enforcement officers in recent years. As a result, law enforcement agencies have made it mandatory for their officers to wear a ballistic vest while on duty.
Ballistic vests have been available in recent years as a protective panel having overlying layers of a fabric made from woven high tensile strength plastic fibers. Woven fabrics made from an aramid fiber known as KELVAR, for example, have been used successfully in ballistic vests because of the high energy absorption properties of the fabric material. The material is also reasonably light in weight and flexible, which provides improved comfort when compared with previous vests which were made of metal and were therefore heavier and more rigid. The comfort of a ballistic vest is extremely important, especially to law enforcement officers, because of the heat build-up that occurs from wearing a heavy and inflexible vest for the long hours an officer is on duty. Resistance to projectile penetration is a principal factor in designing a ballistic vest; and added protective layers can offer greater protection against projectiles having the higher threat levels, but added protective layers also add undesired weight and inflexibility of the vest.
In addition to woven KEVLAR fabric layers, ballistic vests have been made from other high strength plastic fibers and composites to reduce weight and improve flexibility of the vest. However, ballistic vests using the lighter, more flexible materials also must offer the required minimum levels of protection against penetration by different types of projectiles.
Ballistic vests are regularly certified by subjecting them to ballistics testing to measure their ability to protect against different projectiles fired from different types of weapons at various angles. One ballistic test commonly used in the industry is the National Institution of Justice (NIJ) Standard 0101.03 Threat Level IIIA, which, in general terms, is a high performance standard requiring that the ballistic vest prevent penetration of specified .44 Magnum and 9 mm rounds fired at a velocity of at least 1400 ft/sec. In addition to preventing such projectile penetration, "backface deformation" also is a required test factor in the NIJ Standard 0101.03 Threat Level IIIA certification test. Backface deformation measures the trauma level experienced by a projectile that does not penetrate the test panel. According to this test, the maximum allowable backface signature (bfs) containment for soft body armor requires a maximum allowable bfs of 44 mm for .44 Magnum and 9 mm rounds.
There is a need to provide a ballistic vest that is reasonably light in weight, is highly flexible and comfortable, and is also capable of meeting the high performance projectile specifications of NIJ Threat Level IIIA. Providing such a vest at a reasonably low cost for the comparable high performance level also is a desirable objective.
There are other instances where lighter weight vests are more desirable even though they may not meet the Threat Level IIIA standards. Here the challenge is to produce a lightweight vest capable of meeting the certification standards of NIJ Threat Levels II and IIA. An extremely lightweight vest with an areal weight less than one pound per square foot that meets Level II and IIA standards is desirable.